The species lays at the surface of muddy sand or maërl, from 15m deep to shelf depths, in areas subject to significant but not violent streams, and not exposed to swell (Conchylinet).
Original taxon: Mya norwegica. Synonyms: coruscans, elongata, pellucida, striata, truncata…
Above: a specimen devoid of radial ribs.
30-40m deep, Málaga, Andalucia, S. Spain. 41mm.
Both species possess a shell adapted to surface-feeding by filtration in streams (truncated posterior end, flat valves).
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Original pictures provided by Olivier, Morgenroth & Salvador for Wikimedia Commons – (CC BY).
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« Shell oblong-ovate, white, pellucid, thin, and rather convex; umbo small, placed nearly central; posterior side a little truncated, and a little turned to one side; anterior side rounded; covered with a fine transparent olivaceous epidermis; pretty strongly wrinkled concentrically, the wrinkles more strong and sharp, and rather rugose, at each end; the outside is covered with a fine waved striae at each end, but smooth towards the centre of the valves… » – Op. cit. p. 505.
« …from the umbo an oblique furrow runs to the end of the anterior slope; in each valve is a spoon-like cavity, sloping downwards, to which the cartilage is fixed. Inside of a very fine pearlaceous hue, and smoothly wrinkled, corresponding with the outside […] Two opposite valves, of different sizes, of this shell, were found by Miss Hutchins at Bantry Bay, and are now in the cabinet of Dr. Taylor of Dublin, who obligingly favoured me with them, to describe and draw from. » – Ibid.
Specimens from near Atlantic, with weak radials.
Washed ashore, Playa de la Canaleta, Punta Umbria, Huelva, SW. Andalucia, SW. Spain. 22,8mm.
Anatina elongata in S. Hanley: An illustrated and descriptive catalogue of Recent shells, London 1842-1846, plate 13 fig.27. Also labelled Lyonsia (Osteodoma) elongata: « Nearly thrice as broad as long, very inequivalve, beaks situated at 3/7ths the distance from the rounded posterior extremity, ventral and dorsal edges but little curved, subparallel in the centre; anteriorly subrostrated but truncated at the extremity, the gape very large; very fragile, pellucid, the epidermis with fine radiating lines not visible on the disc. » – Op. cit. p.25.